Balloon design to reduce distal length

ABSTRACT

A device and system for thermally affecting tissue that includes a balloon catheter with a reduced distal length for ease of navigation and that also includes a balloon that is more resistant to bursting and delamination. The balloon may include a proximal neck generally attached to an elongate body and a distal neck generally attached to a shaft disposed within the elongate body. The distal neck is turned inward to extend within the balloon chamber and the proximal neck may either extend within the chamber or extend proximally away from the balloon chamber. Alternatively, the device may include an inner balloon and an outer balloon, the distal necks of both being turned inward and extending within the inner balloon chamber. The proximal necks may both also be turned inward to extend within the chamber or the proximal neck of the outer balloon may extend away from the balloon chamber.

CROSS-REFERENCE TO RELATED APPLICATION

n/a

STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT

n/a

FIELD OF THE INVENTION

The present invention relates generally to catheters and methods forperforming targeted tissue ablation in a subject. In particular, thepresent invention provides devices comprising catheters having balloonsconfigured to reduce the distal length of the device and to reducelikelihood of delamination of the balloon from the catheter body.

BACKGROUND OF THE INVENTION

Tissue ablation is used in numerous medical procedures to treat apatient. Ablation can be performed to remove undesired tissue such ascancer cells. Ablation procedures may also involve the modification ofthe tissue without removal, such as to stop electrical propagationthrough the tissue in patients with an arrhythmia. The ablation is oftenperformed by passing energy, such as electrical energy, through one ormore electrodes causing the tissue in contact with the electrodes toheats up to an ablative temperature, but may also be performed byfreezing the tissue with the use of a cryoablation catheter.

Cryoablation catheters typically include an expandable element, such asa balloon, at the distal end. Although there are significant advantagesof using balloons for cryoablation techniques, there are oftenassociated disadvantages. First, to provide adequate attachment strengthbetween a balloon and the catheter, the distal end of the balloon isoften attached to a device distal tip, which may extend distally beyondthe balloon. A balloon catheter with a distal tip can be difficult toposition within the body, for example the right or left atrium of theheart. For a cryoablation technique to be effective, the distal end mustbe articulated with great accuracy to contact the balloon with thetarget tissue. Additionally, this technique is often performed in a verysmall space. A catheter with a long distal tip (one that extends pastthe distal neck of the balloon) or a balloon with extended distal and/orproximal necks can exaggerate steering problems.

Second, there is the concern that the balloon will burst from theapplication of pressurized cryofluid within, or the seal between theballoon and the body or shaft of the catheter will come undone(delamination). For the typically shaped catheter balloon, a balloonwith a conical or ellipsoidal body and two necks, the outward pressureexerted on the balloon pushes the balloon material away from thecatheter body or shaft. Longer necks with more attachment surface areaare needed to securely attach the balloon to the catheter and preventdelamination due to the forces of pressure. This, in turn, createslonger balloons at the catheter distal tip that are more difficult tosteer and precisely contact with target tissue.

In light of the above, it is the object of the present invention toprovide a cryoablation catheter with a shortened distal tip that notonly is more easily manipulated within small spaces, but that alsoincludes a balloon that is more resistant to delamination from thecatheter body or shaft by making use of the balloon pressure to helpreduce the tensile stress on the sealing or bonding agent. Currentlyused devices with balloons having everted necks experience the oppositeeffect, with the balloon pressure contributing to delamination.Additionally, glue joints are not particularly good at resisting tensilestress, unless in compression. It is another object to provide a methodof using a cryoablation catheter with a shortened distal tip.

SUMMARY OF THE INVENTION

The present invention advantageously provides a medical system,specifically a balloon catheter, that is more easily navigated withinthe body and that includes a balloon that is more resistant to burstingand delamination. In one embodiment, a medical device for thermallyaffecting tissue may include an elongate body, a shaft that is slidablydisposed within the elongate body, an inflatable element (for example, aballoon) defining a chamber and having a proximal neck coupled to theelongate body and forming a proximal seal, and also having a distal neckcoupled to the shaft and forming a distal seal that is substantiallycoterminous with the shaft, the distal seal being between the inflatableelement and the shaft and extending within the chamber of the inflatableelement. The proximal neck and the distal neck each may include an outersurface and an inner surface, the distal seal being formed between theouter surface of the distal neck and a distal portion of the shaft. Theproximal seal may extend within the chamber of the inflatable element.For example, the proximal seal may be formed between the outer surfaceof the proximal neck and a distal portion of the elongate body.Alternatively, the proximal seal may be external to the chamber of theexpandable element and extend along the elongate body in a proximaldirection from the chamber of the expandable element. In eitherembodiment, the proximal seal and the distal seal may each define alength of approximately 10% to 30% of the total length of the expandableelement when the expandable element is inflated. The shaft and theexpandable element may be coterminous and may define a distal face thatis substantially continuous.

In another embodiment, a medical device for thermally affecting tissuemay include an elongate body, a shaft that is movably disposed withinthe elongate body, a first balloon disposed within a second balloon,each balloon defining a chamber and having at least one proximaladhesive junction and at least one distal adhesive junction, the secondballoon when expanded defining a substantially continuous surface withthe distal end of the shaft. The at least one distal adhesive junctionof the first balloon may be between the first balloon and the shaft andextend within the chamber of the first balloon, and the at least onedistal adhesive junction of the second balloon may be between the secondballoon and the first balloon and extend within the chamber of the firstballoon. The first balloon may be asymmetrically positioned within thesecond balloon, with the at least one proximal adhesive junction of thefirst balloon being one proximal adhesive junction between the firstballoon and the elongate body and extending within the chamber of thefirst balloon, and the at least one proximal adhesive junction of thesecond balloon being one proximal adhesive junction between the secondballoon and the elongate body and extending proximally along theelongate body external to the chamber of the first balloon. The proximaladhesive junction of the first balloon may be located a distance alongthe elongate body from the proximal adhesive junction of the secondballoon, the distance defining an interstitial space between the firstballoon and the second balloon. Further, the at least one distaladhesive junction of the first balloon may define a length that isgreater than the length defined by the at least one distal adhesivejunction of the second balloon. Alternatively, the first balloon may besymmetrically positioned within the second balloon, with the at leastone proximal adhesive junction of the first balloon including anadhesive junction between the first balloon and the elongate body andthe second balloon, the at least one proximal adhesive junction of thefirst balloon and the at least one adhesive junction of the secondballoon both extending within the chamber of the first balloon.Alternatively, the first balloon may be symmetrically positioned withinthe second balloon, the at least one proximal adhesive junction of thefirst balloon being one proximal adhesive junction between the firstballoon and the elongate body and extending within the chamber of thefirst balloon, and the at least one proximal adhesive junction of thesecond balloon being one proximal adhesive junction between the secondballoon and the elongate body and extending proximally along theelongate body external to the chamber of the first balloon. The at leastone distal adhesive junction and the at least one proximal adhesivejunction of the first balloon may extend within the chamber of the firstballoon each define a length of approximately 10% to 30% of the totalinflated balloon length. Further, the second balloon may define a distalface when inflated, and the shaft may be coterminous with the distalface.

In another embodiment, a medical device for thermally affecting tissuemay include: an elongate body defining a proximal portion, a distalportion, and a lumen therebetween; a shaft slidably disposed within thecatheter body lumen, the shaft defining a proximal portion and a distalportion; a first balloon disposed within a second balloon, each balloondefining a chamber and having a proximal neck coupled to the distalportion of catheter body to form a proximal seal, and each balloonhaving a distal neck coupled to the distal portion of the shaft to formadistal seal that is substantially coterminous with the distal portion ofthe shaft; a fluid injection conduit disposed within the chamber of thefirst balloon; the first balloon being symmetrically positioned withinthe second balloon, with the proximal seal of the first ballooncomprising an adhesive junction between the first balloon and the distalportion of the catheter body and extending within the chamber of thefirst balloon, and the proximal seal of the second balloon comprising anadhesive junction between the second balloon and the distal portion ofthe catheter body at a distance proximal to the proximal seal of thefirst balloon, the proximal seal of the second balloon extendingexternally to the chamber of the first balloon; the at least one distalseal of the first balloon comprising an adhesive junction between thefirst balloon and the distal portion of the shaft and also comprising anadhesive junction between the first and second balloons, the distal sealof the first balloon extending within the chamber of the first balloon;the second balloon defining a distal face when inflated, the shaft beingcoterminous with the distal face; and the proximal seal and the distalseal of the first balloon each defining a length of approximately 10% to30% of the inflated balloon length.

BRIEF DESCRIPTION OF THE DRAWINGS

A more complete understanding of the present invention, and theattendant advantages and features thereof, will be more readilyunderstood by reference to the following detailed description whenconsidered in conjunction with the accompanying drawings wherein:

FIG. 1A is an illustration of a generalized medical system constructedin accordance with the principles of the present invention;

FIG. 1B is a cross-sectional view of the elongate body of a medicaldevice;

FIG. 2 is a perspective view of a first embodiment of a medical device,in which both the proximal and distal necks are inverted;

FIG. 3 is a perspective view of a second embodiment of a medical device,in which the proximal neck is everted and the distal neck is inverted;

FIG. 4 is a cross-sectional view of the first embodiment of the medicaldevice of FIG. 2, in which the both the proximal and distal necks areinverted;

FIG. 5 is a cross-sectional view of the second embodiment of the medicaldevice of FIG. 3, in which the proximal neck is everted and the distalneck is inverted;

FIG. 6 is a cross-sectional view of a third embodiment of a medicaldevice, the device having two balloons with a first balloonsymmetrically positioned within a second balloon and the proximal anddistal necks of both balloons being inverted;

FIG. 7 is a cross-sectional view of a fourth embodiment of a medicaldevice, the device having two balloons with a first balloonasymmetrically positioned within a second balloon and the proximal anddistal necks of both balloons being inverted;

FIG. 8 is an illustration of a cross-sectional view of a fifthembodiment of a medical device, the device having two balloons with afirst balloon symmetrically positioned within a second balloon and thedistal necks of both balloons being inverted, the proximal neck of thefirst balloon being inverted, and the proximal neck of the secondballoon being everted; and

FIG. 9 is a cross-sectional view of a sixth embodiment of a medicaldevice, the device having two balloons with a first balloonasymmetrically positioned within a second balloon and the distal necksof both balloons being inverted, the proximal neck of the first balloonbeing inverted, and the proximal neck of the second balloon beingeverted.

DETAILED DESCRIPTION OF THE INVENTION

The present invention advantageously provides a medical system,specifically, a balloon catheter, that is more easily navigated withinthe body of a patient and that includes a balloon that is more resistantto bursting and delamination. Referring now to the drawing figures inwhich like reference designations refer to like elements, an embodimentof a medical system constructed in accordance with principles of thepresent invention is shown in FIG. 1A and generally designated as “10.”The system 10 generally includes a medical device 12 that may be coupledto a control unit 14 or operating console. The medical device 12 maygenerally include one or more treatment regions, including at least oneballoon 16, for energetic or other therapeutic interaction between themedical device 12 and a treatment site. The treatment region(s) maydeliver, for example, cryogenic therapy, radio frequency energy, orother energetic transfer with a tissue area in proximity to thetreatment region(s), including cardiac tissue.

The medical device 12 may include an elongate body 18 passable through apatient's vasculature and/or proximate to a tissue region for diagnosisor treatment, such as a catheter, sheath, or intravascular introducer.The elongate body 18 may define a proximal portion 20 and a distalportion 22, and may further include one or more lumens disposed withinthe elongate body 18 thereby providing mechanical, electrical, and/orfluid communication between the proximal portion of the elongate body 18and the distal portion of the elongate body 18, as discussed in moredetail below.

The medical device 12 may include a rigid or semi-rigid shaft 24 atleast partially disposed within a portion of the elongate body 18. Theshaft 24 may extend or otherwise protrude from a distal end of theelongate body 18, and may be movable with respect to the elongate body18 in longitudinal and rotational directions. That is, the shaft 24 maybe slidably and/or rotatably moveable with respect to the elongate body18. The shaft 24 may further define a lumen 26 therein for theintroduction and passage of a guide wire. The shaft 24 may comprise aplurality of sections, each section having a varying diameter, with theshaft terminating in or otherwise including an area having a largerdiameter than the rest of the shaft 24, which may be referred to as adistal tip 28. The distal tip 28 may define an opening and passagetherethrough that is in communication with the shaft lumen 26. Asdiscussed in greater detail below, the balloon 16 may be attached to thedistal tip 28. However, it will be understood that the shaft 24 may havea single continuous diameter with the balloon 16 being attached to theshaft proximate the distal end of the shaft.

The medical device 12 may further include a fluid delivery conduit 30traversing at least a portion of the elongate body 18 and towards thedistal portion 22. The delivery conduit 30 may be coupled to orotherwise extend from the distal portion 22 of the elongate body 18 intothe balloon 16. The delivery conduit 30 may, for example, be wrapped orcoiled about at least a portion of the shaft 24 within the balloon, asshown in FIG. 1A. Alternatively, the delivery conduit 30 may beotherwise coupled to the shaft 24 of the medical device 12, or may bedisposed within the shaft 24 with the shaft defining one or moreopenings through which fluid may pass into the balloon (for example, asshown in FIG. 4). Alternatively, the fluid delivery conduit 30 may beflexible, constructed from a shape memory material (such as Nitinol),and/or include other controllably deformable materials that allow thefluid delivery conduit 30 to be manipulated into a plurality ofdifferent geometric configurations, shapes, and/or dimensions. Althougha fluid delivery conduit is not expressly shown in FIGS. 5-9 forsimplicity, it will be understood that the devices shown in all figuresmay have any suitable, fluid delivery conduit including those shown inFIGS. 1A and 4.

The fluid delivery conduit 30 may define a lumen therein for the passageor delivery of a fluid from the proximal portion of the elongate body 18and/or the control unit 14 to the distal portion and/or treatment regionof the medical device 12. The fluid delivery conduit 30 may furtherinclude one or more apertures or openings therein to provide for thedispersion or directed ejection of fluid from the lumen to the interiorchamber 34 of the balloon 16. 24

The medical device 12 may further include a handle 44 coupled to theproximal portion 20 of the elongate body 18. The handle 44 can includecircuitry for identification and/or use in controlling of the medicaldevice 12 or another component of the system 10. For example, the handle44 may include one or more pressure sensors 46 to monitor the fluidpressure within the medical device 12. Additionally, the handle 44 maybe provided with a fitting 48 for receiving a guide wire that may bepassed into the guide wire lumen 26. The handle 44 may also includeconnectors 50 that are matable directly to a fluid supply/exhaust andcontrol unit 14 or indirectly by way of one or more umbilicals. Thehandle 44 may further include blood detection circuitry in fluid and/oroptical communication with the injection, exhaust and/or interstitiallumens. The handle 44 may also include a pressure relief valve in fluidcommunication with the fluid delivery conduit 30 and/or exhaust lumen toautomatically open under a predetermined threshold value in the eventthat value is exceeded.

The handle 44 may also include one or more actuation or control featuresthat allow a user to control, deflect, steer, or otherwise manipulate adistal portion of the medical device from the proximal portion of themedical device. For example, the handle 44 may include one or morecomponents such as a lever or knob 52 for manipulating the elongate body18 and/or additional components of the medical device 12. For example, apull wire with a proximal end and a distal end may have its distal endanchored to the elongate body 18 at or near the distal portion 22. Aproximal end of the pull wire 54 may be anchored to an element such as acam in communication with and responsive to the lever 52. A distal endof the pull wire 54 may be attached or coupled to a portion of elongatebody 18 or the shaft 24. As a non-limiting example, the pull wire 54 maybe coupled to a coupling element 55 that is, in turn, coupled to theshaft 24 (as shown in the figures). However, it will be understood thatthe pull wire 54 may be coupled to the device in any manner suitable tocreate at least one point of inflection (that is, a location at whichthe device may bend during navigation through the patient's vasculature)in a desired location on the elongate body 18 and/or the treatmentelement. The medical device 12 may include an actuator element 56 thatis movably coupled to the proximal portion of the elongate body 18and/or the handle 44. The actuator element 56 may further be coupled toa proximal portion of the shaft 24 such that manipulating the actuatorelement 56 in a longitudinal direction causes the shaft 24 to slidetowards either of the proximal or distal portions of the elongate body18. The actuator element 56 may include a thumb-slide, a push-button, arotating lever, or other mechanical structure for providing a movablecoupling to the elongate body 18, the handle 44, and/or the shaft 24.Moreover, the actuator element 56 may be movably coupled to the handle44 such that the actuator element is movable into individual, distinctpositions, and is able to be releasably secured in any one of thedistinct positions. The handle 44 may also include one or morerotational actuator elements for rotating the shaft 24 and/or a guidewire.

The control unit 14 may include one or more computers 58 that includeone or more processors for receiving signals from one or more sensorsthroughout the system 10, and or for the automatic, semi-automatic,and/or manual operation of the system. For example, the system 10 mayinclude one or more computers 58 having one or more user input devicesby which a user can program system parameters such as the inflation anddeflation of a balloon, circulation of coolant through the fluiddelivery and recovery conduits, and/or the operation of one or moreelectrodes or other thermal delivery elements. Additionally, the usermay use the user input devices to override the automatic operation ofthe system 10 either programmed into or predetermined by the controlunit 14.

The system 10 may further include one or more sensors to monitor theoperating parameters throughout the system, including for example,pressure, temperature, flow rates, volume, or the like in the controlunit 14 and/or the medical device 12, in addition to monitoring,recording or otherwise conveying measurements or conditions within themedical device 12 or the ambient environment at the distal portion ofthe medical device 12. The sensor(s) may be in communication with thecontrol unit 14 for initiating or triggering one or more alerts ortherapeutic delivery modifications during operation of the medicaldevice 12. One or more valves, controllers, or the like may be incommunication with the sensor(s) to provide for the controlleddispersion or circulation of fluid through the lumens/fluid paths of themedical device 12. Such valves, controllers, or the like may be locatedin a portion of the medical device 12 and/or in the control unit 14.

In an exemplary system, a fluid supply 60 including a coolant, cryogenicrefrigerant, or the like, an exhaust or scavenging system for recoveringor venting expended fluid for re-use or disposal, as well as variouscontrol mechanisms for the medical system may be housed in the controlunit 14. In addition to providing an exhaust function for the catheterfluid supply, the console may also include pumps, valves, controllers orthe like to recover and/or re-circulate fluid delivered to the handle,the elongate body, and/or the fluid pathways of the medical device 12. Avacuum pump 62 in the control unit 14 may create a low-pressureenvironment in one or more conduits within the medical device 12 so thatfluid is drawn into the conduit(s)/lumen(s) of the elongate body 18,away from the distal portion and towards the proximal portion of theelongate body 18. For example, the control unit 14 may include a fluidrecovery reservoir 64 that is in fluid communication with a fluidrecovery conduit 66 that is, in turn, in fluid communication with theballoon 16. The control unit 14 may include one or more controllers,processors, and/or software modules containing instructions oralgorithms to provide for the automated operation and performance of thefeatures, sequences, or procedures described herein.

While the medical device 12 may be in fluid communication with acryogenic fluid source to cryogenically treat selected tissue, it isalso contemplated that the medical device 12 may alternatively oradditionally include one or more electrically conductive portions orelectrodes thereon coupled to a radio frequency generator or powersource as a treatment or diagnostic mechanism.

Referring now to FIG. 1B, a non-limiting cross-sectional view of theelongate body 18 of the device is shown. The elongate body 18 maygenerally include an inner lumen 67, one or more pull wire lumens 68,and, optionally, one or more outer lumens 70. The inner lumen 67 may besheathed by or defined by a layer of braided wire and/or a layer ofTeflon (not shown for simplicity). The sheath 24 and fluid deliveryconduit 30 may be disposed within the inner lumen 67, and the spacewithin the inner lumen 67 surrounding the sheath 24 may be incommunication with the vacuum 62 for the removal of expanded coolantfrom the distal end of the device. One or more pull wires 54 may belocated within the one or more pull wire lumens 68 on the outside of theinner lumen 67, although the pull wire 54 is shown in FIGS. 1A and 4-9The one or more outer lumens 70 may serve as conduits for additionalfluids, wires, sensors, or the like. However, it will be understood thatother suitable configurations of interior components and lumens may alsobe used.

Referring now to FIGS. 1A through 9, at least one balloon 16 may be atthe distal portion of the medical device 12. The at least one balloon 16may be coupled to a portion of the elongate body 18 and also coupled toa portion of the shaft 24 to contain a portion of the fluid deliveryconduit 30 therein, as shown and discussed in more detail in FIGS. 2-9.Each balloon 16 may each define an interior chamber or region 34. Forexample, coolant or fluid dispersed from the fluid delivery conduit 30may circulate within the interior chamber 34, and the interior chamber34 may be in fluid communication with the fluid recovery conduit 66defined by or included in the elongate body 18 for the removal ofdispersed coolant from the interior chamber 34 of the balloon 16. Inembodiments in which the device 12 includes more than one balloon, anadditional fluid delivery conduit and/or fluid recovery conduit mayfluidly connect the additional balloons to the control unit 14. The atleast one balloon 16 may further include one or more material layersproviding for puncture resistance, radiopacity, or the like.

As shown in FIGS. 2-9, the distal end of the shaft 24, for example, thedistal tip 28, may be rounded to match the curvature of a balloon 16when inflated, such that the balloon 16 may define a distal face 72having a substantially continuous surface, without the shaft 24protruding beyond the balloon distal face 72. Further, the distal tip 28or distal end of the shaft 24 may be manufactured with a curved distalsurface that matches a curve in the balloon distal face 72, enhancingthe continuity between the shaft 24 and the distal face 72. The shaft isdepicted in FIGS. 2 and 3 as “24/28” to include embodiments in which theballoon 16 is generally coupled to the distal portion of the shaft 24and embodiments in which the balloon 16 is coupled to a distal tip 28 inparticular. As a non-limiting embodiment, the distal face 72 may beslightly curved or arcuate, creating an atraumatic surface for safenavigation through the patient's vasculature and within the patient'sheart. A substantially continuous arcuate surface without anyprojections may facilitate steering of the distal end of the medicaldevice within the patient, especially in small spaces such as thechambers of the heart or vasculature. Although the balloon is shown inthe figures as having a substantially spherical or rounded cubic shape,it will be understood that the balloon may have any suitable shape thatallows for the inclusion of a shortened distal tip.

The medical device 12 may include a single balloon 16, as seen in FIGS.4 and 5. The balloon 16 may have a proximal neck 80 at which the balloon16 is coupled, by an adhesive junction or other joining means, to thedistal portion 22 of the elongate body 18, and may further have a distalneck 82 at which the balloon 16 is coupled, by an adhesive junction orother joining means, to a distal portion of the shaft 24, such as thedistal tip 28. The distal neck 82 of the balloon 16 may be turned inward(in a distal-to-proximal direction) extending within the chamber 34 ofthe balloon 16. This may be referred to as the distal neck 82 beinginverted. The inward extension of the distal neck 82 may form a distalseal 84 that is substantially coterminous with the shaft 24, and maydefine a length of approximately 10% to 30% of the total length of theballoon 16 when the balloon is in an inflated state. The length of theinflated and uninflated balloon may be measured as a straightlinedistance between the proximalmost point and the distalmost point of theballoon 16. In the figures, all seals, which may also be referred to as“adhesive junctions,” are stylistically depicted with hash marks forclarity.

As seen in FIG. 4, the expandable element may be substantially toroidalin shape, with the proximal neck 80 also being inverted (that is, turnedinward, extending in a proximal-to-distal direction). In thisconfiguration, an outer surface of the proximal neck 80 may be bonded,adhered, or otherwise in contact with and attached to an outer surfaceof the distal portion 22 of the elongate body 18 to create a proximalseal 86 extending within the balloon interior chamber 34. The proximalseal 86 may define a length of approximately 10% to 30% of the totallength of the balloon 16 when in an inflated state. Alternatively, asseen in FIG. 5, the balloon 16 may include a proximal neck 80 that iseverted (that is, turned outward, extending in a distal-to-proximaldirection). In this configuration, an inner surface of the proximal neck80 may be bonded, adhered, or otherwise in contact with and attached toan outer surface of the distal portion 22 of the elongate body 18 tocreate a proximal seal 86 extending without (that is, being external to)the balloon interior chamber 34 along an outer surface of the distalportion 22 of the elongate body 18. Further, the proximal neck 80 may becoupled to the distal portion 22 of the elongate body 18 such that theproximal neck 80 (proximate the balloon chamber 34) and the elongatebody 18 are coterminous (for example, as shown in FIG. 4), or theproximal neck 80 may be coupled to the distal portion 22 of the elongatebody 18 such that a portion of the elongate body 18 extends within thechamber 34 (for example, as shown in FIG. 5). In all embodiments, theballoon 16 may define a distal face 72 that has a substantiallycontinuous surface that facilitates navigation of the device within thepatient.

The medical device 12 may include more than one balloon. For example,FIGS. 6-9 show a medical device 12 having an inner balloon 88 and anouter balloon 90. The inner 88 and outer 90 balloons together maycomprise the treatment element 91. The inner balloon 88 may contain aportion of the fluid delivery conduit 30 therein, and the outer balloon90 may be disposed about the inner balloon 88. The inner 88 and outer 90balloons in FIGS. 6-9 may be substantially similar to the single balloon16 shown and described in the other figures, in composition, function,attachment, etc. The inner 88 and outer 90 balloons may be locatedsubstantially adjacent to or in contact with each other, and may definean interstitial space 92 between the balloons 88, 90 to facilitatedetection and prevention of leaks from the first 88. For example, one ormore sensors (such as impedance sensors, pressure sensors, and/ortemperature sensors) may be located within the interstitial space todetect fluid leaks. In the embodiments shown in FIGS. 6 and 8, theinterstitial space 92 may be very thin, even absent in some areas,especially when the inner balloon 88 is inflated and in contact with theouter balloon 90. In the embodiments shown in FIGS. 7 and 9, however,the interstitial space 92 may be larger in at least a portion of thetreatment element. The two-balloon configuration may add strength to thetreatment element, in that a delamination force resulting from inflationof the inner balloon 88 would have to overcome the seals of both theinner and outer balloons for the treatment element 91 to delaminate.

As shown in FIGS. 6-9, each of the inner 88 and outer 90 balloons mayhave a proximal neck 94, 96 coupled to an outer surface of the distalportion 22 of the elongate body 18, and a distal neck 98, 100 coupled toa portion of the shaft 24, for example, the distal tip 28. In all ofFIGS. 6-9, the outer balloon 90 may define a distal face 72 that has asubstantially continuous surface that facilitates navigation of thedevice within the patient. For example, the shaft 24 or distal tip 28may be substantially coterminous with the distal balloon 90.

Continuing to refer to FIGS. 6-9, the inner balloon 88 may besubstantially toroidal in shape, with the proximal neck 94 beinginverted (that is, turned inward, in a proximal-to-distal direction) toform a first proximal seal 102 between an outer surface of the proximalneck 94 and an outer surface of the distal portion 22 of the elongatebody 18, and the distal neck 98 being inverted (that is, turned inward,in a distal-to-proximal direction) to form a first distal seal 104between an outer surface of the distal neck 98 and a distal portion ofthe shaft 24 (for example, the distal tip 28), each seal 102, 104extending within the interior chamber 34 of the inner balloon 88.Although the seals 102, 104 could also be described as extended withinthe interior chamber of the second balloon 90, the description islimited to extension within the interior chamber 34 of the inner balloon88 for simplicity of reference. As is discussed in more detail below,the first proximal seal 102 and the first distal seal 104 of the innerballoon 88 may be attached to the elongate body 18 and shaft 24,respectively. A second portion of each neck 94, 98 may be in contactwith or substantially in contact with, but not attached to, a portion ofthe proximal and distal necks of the outer balloon 90. As such, fluidleaking from the inner balloon 88 may more easily flow between the inner88 and outer 90 balloons for detection by a leak-detection sensordisposed in the interstitial space 92, such as a pressure or impedancesensor. The distal neck 98 and proximal neck 94 of the inner balloon 88may each define a length of approximately 10% to 30% of the total lengthof the inner balloon 88 when the inner balloon 88 is in an inflatedstate, with the length of each neck 94, 98 being measured as astraightline distance between the proximalmost point and the distalmostpoint of the inner balloon 88.

The distal neck 100 of the outer balloon 90 may also be inverted (thatis, turned inward, in a distal-to-proximal direction), extending withinthe interior chamber 34 of the inner balloon 88. An outer surface of thedistal neck 100 of the outer balloon 90 may be bonded, adhered, orotherwise in contact with and attached to an outer surface of a distalportion of the shaft 24 (for example, the distal tip 28) to create adistal seal 110 extending within the interior chamber 34 of the innerballoon 88. An inner surface of distal neck 100 of the outer balloon 90may also be in contact with or substantially in contact with, but notattached to, an outer surface of the distal neck 98 of the inner balloon88. At least a portion of the distal neck 98 of the inner balloon 88 mayoverlap the inverted distal neck 100 of the outer balloon 90.

Now referring in particular to FIGS. 6 and 7, the proximal neck 96 ofthe outer balloon 90 may also be inverted (that is, turned inward, in aproximal-to-distal direction), extending within the interior chamber 34of the inner balloon 88. An outer surface of the outer balloon proximalneck 96 may be bonded, adhered, or otherwise in contact with andattached to an outer surface to the distal portion 22 of the elongatebody 18 to form a proximal seal 112. The inner balloon 88 may besymmetrically or asymmetrically positioned within the outer balloon 90,depending on, for example, the desired maneuverability of the device,the procedure for which the device is used, and/or the desired coolingeffect of the treatment element. For example, the device shown in FIG. 6may have a more distal deflection point than the device shown in FIG. 7,because the layered proximal necks 94, 96 of the inner 88 and outer 90balloons may increase the stiffness and decrease the flexibility of thedevice at or near the location at which the proximal necks 94, 96 areattached to the elongate body 18. This more distal deflection point mayallow the device to be navigated through tortuous vasculature moreeasily. Additionally, the asymmetrical configuration shown in FIG. 7 mayaffect the cooling capacity of the treatment element 91. The largerinterstitial space 92 between the inner 88 and outer 90 balloons mayprovide thermal insulation of the inner balloon 88, particularly theproximal portion of the inner balloon 88, from the warming effect of thesurrounding blood. This, in turn, may enhance the cooling effect of, atleast, the distal portion of the treatment element through the outerballoon 90. That is, the limited heat transfer from tissue to theproximal portion of the inner balloon 88 may preserve and potentiallyconcentrated the cooling capacity within the distal portion of thetreatment element 91. The symmetrical configuration shown in FIG. 6 mayallow cooling of both the proximal and distal portions of the treatmentelement 91. In a non-limiting embodiment, this symmetrical configurationmay be useful when the device is inserted into the left atrium through apulmonary vein, and then retracted so that the proximal portion of thetreatment element 91 is in contact with the pulmonary vein ostium. Inthat case, the proximal portion, rather than the distal portion, of thetreatment element 91 may be used to thermally treat the pulmonary veinostium.

FIG. 6 shows a configuration in which the inner balloon 88 issymmetrically positioned within, and concentric with, the outer balloon90. Both the inner 88 and outer 90 balloons in FIG. 6 may be toroidal inshape, with the proximal necks 94, 96 and distal necks 98, 100 of theballoons being inverted and extending within the interior chamber 34 ofthe inner balloon 88. In such an embodiment, an inner surface of theproximal neck 96 of the outer balloon 90 may be in contact with orsubstantially in contact with, but not attached to, an outer surface ofthe proximal neck 94 of the inner balloon 88. At least a portion of theproximal neck 94 of the inner balloon 88 may overlap the proximal neck96 of the outer balloon 90. In this manner, a double-layered adhesivejunction may be formed, which may further prevent delamination ortearing from occurring when the balloons are inflated and burst pressureis exerted.

FIG. 7 shows a configuration in which the inner balloon 88 may beasymmetrically positioned within the outer balloon 90. Both the inner 88and outer 90 balloons may be toroidal in shape, but may not beconcentric, unlike the configuration shown in FIG. 6. In theconfiguration shown in FIG. 7, the proximal neck 96 of the outer balloon90 may be bonded, adhered, or otherwise in contact with and attachedonly to the distal portion 22 of the elongate body 18, without beingoverlapped by and coupled to at least a portion of the proximal neck 94of the inner balloon 88. Further, the proximal neck 96 of the outerballoon 90 may not extend within the interior chamber 34 of the innerballoon 88, but may instead extend within the interstitial space 92between the inner 88 and outer 90 balloons. Defined another way, theproximal neck 96 of the outer balloon 90 may be inverted within thetreatment element 91 as a whole. As shown in FIG. 7, the portion ofinterstitial space 92 proximate the proximal necks 94, 96 of the inner88 and outer 90 balloons may be larger than the portion of interstitialspace 92 proximate the distal necks 98, 100 of the inner 88 and outer 90balloons. This size of the interstitial space 92 proximal the proximalnecks 94, 96 may be determined by the distance between the proximal seal102 of the inner balloon 88 and the proximal seal 112 of the outerballoon 90.

Referring now to FIGS. 8 and 9, the proximal neck 96 of the outerballoon 90 may be everted (that is, turned outward, in adistal-to-proximal direction), extending without or being external toboth the interior chamber 34 of the inner balloon 88 and theinterstitial space 92 between the inner 88 and outer balloons 90.Defined another way, the proximal neck 96 of the outer balloon 90 may beeverted on the outside of the treatment element 91 as a whole. An innersurface of the proximal neck 96 of the outer balloon 90 may be bonded,adhered, or otherwise in contact with and attached to the distal portion22 of the elongate body 18 to form a first proximal seal 112. The innerballoon 88 may be symmetrically or asymmetrically positioned within theouter balloon 90, with the advantages of each configuration being asdiscussed above regarding FIGS. 6 and 7.

FIG. 8 shows a configuration in which the inner balloon 88 issymmetrically positioned within, and concentric with, the outer balloon90. In such an embodiment, the proximal neck 96 of the outer balloon 90may not be coupled to the proximal neck 94 of the inner balloon 88, butthe proximal seal 112 of the outer balloon 90 and the proximal seal 102of the inner balloon 88 may be substantially adjacent to each other,extending in opposite directions. For example, as shown in FIG. 8, theproximal seal 112 of the outer balloon 90 may extend be everted (thatis, external to the treatment element 91) in a distal-to-proximaldirection, and the proximal seal 102 of the inner balloon 88 may beinverted and extend within the interior chamber 88 (and the treatmentelement 91 as a whole) in a proximal-to-distal direction. Theinterstitial space 92 defined between the inner 88 and outer 90 balloonsmay only be wide enough to facilitate leak detection or leak containmentwithin the outer balloon 90.

FIG. 9 shows a configuration in which the inner balloon 88 isasymmetrically positioned within the outer balloon 90. In such anembodiment, the proximal neck 96 of the outer balloon 90 may be coupledonly to an outer surface of the distal portion 22 of the elongate body18, without being coupled to the proximal neck 94 of the inner balloon88. As shown in FIG. 9, the portion of interstitial space 92 proximalthe proximal necks 94, 96 of the inner 88 and outer 90 balloons may belarger than the portion of interstitial space 92 proximate the distalnecks 98, 100 of the inner 88 and outer 90 balloons. The size of theinterstitial space 92 between the proximal necks 94, 96 may bedetermined by the distance between the proximal seal 102 of the innerballoon 88 and the proximal seal 112 of the outer balloon 90.

The continuously arcuate configuration of the distal portion of themedical device generally provides the ability to deliver therapeutictreatment more precisely, because of the absence of a protruding distaltip enhances ease of navigating the device. Further, shape and sealcharacteristics of the balloons allow for a more even distribution ofpressure exerted by the cryogenic fluid. Balloons with outward sealsoften experience delamination and bursting because all the pressureexerted within the balloon is pushing outward, essentially pulling theballoon away from the medical device. In contrast, the seals of balloonsas presented herein are strengthened with increased pressure because thecryogenic fluid, as it is expelled in an outward direction and deflectedfrom the balloon surface within the chamber of the balloon, pressesagainst the inverted necks and reinforces the seals. Although notexpressly shown, it will be understood that a configuration may bepresented in which the distal necks 98, 100 of the inner 88 and outer 90balloons may be inverted, whereas both proximal necks 94, 96 may beeverted and attached to the device in the manner shown and described inFIGS. 6-9).

It will be appreciated by persons skilled in the art that the presentinvention is not limited to what has been particularly shown anddescribed herein above. In addition, unless mention was made above tothe contrary, it should be noted that all of the accompanying drawingsare not to scale. Of note, the system components have been representedwhere appropriate by conventional symbols in the drawings, showing onlythose specific details that are pertinent to understanding theembodiments of the present invention so as not to obscure the disclosurewith details that will be readily apparent to those of ordinary skill inthe art having the benefit of the description herein. Moreover, whilecertain embodiments or figures described herein may illustrate featuresnot expressly indicated on other figures or embodiments, it isunderstood that the features and components of the system and devicesdisclosed herein are not necessarily exclusive of each other and may beincluded in a variety of different combinations or configurationswithout departing from the scope and spirit of the invention. A varietyof modifications and variations are possible in light of the aboveteachings without departing from the scope and spirit of the invention,which is limited only by the following claims.

What is claimed is:
 1. A medical device for thermally affecting tissuecomprising: an elongate body; a shaft disposed in the elongate body andbeing movable relative to the elongate body when the device is in use,the shaft having a distalmost end face; and a first balloon disposedwithin a second balloon, each balloon defining a chamber and having aproximal adhesive junction and a distal adhesive junction, the secondballoon when expanded having a curvature and a distal face, thedistalmost end face of the shaft being curved such that distal face ofthe second balloon when inflated and the distalmost end face of theshaft together define a continuous curved surface, each of the firstballoon and the second balloon having an outer surface, the distaladhesive junction of the first balloon being between the outer surfaceof the first balloon and the shaft, and the distal adhesive junction ofthe second balloon being between the outer surface of the second balloonand the shaft.
 2. The medical device of claim 1, wherein the distaladhesive junction of the first balloon extends within the chamber of thefirst balloon, and the distal adhesive junction of the second balloonextends within the chamber of the first balloon.
 3. The medical deviceof claim 2, wherein the first balloon is asymmetrically positionedwithin the second balloon, with the proximal adhesive junction of thefirst balloon being between the first balloon and the elongate body andextending within the chamber of the first balloon, and proximal adhesivejunction of the second balloon being between the second balloon and theelongate body and extending proximally along the elongate body externalto the chamber of the first balloon.
 4. The medical device of claim 2,wherein the proximal adhesive junction of the first balloon is located adistance along the elongate body from the proximal adhesive junction ofthe second balloon, the distance defining an interstitial space betweenthe first balloon and the second balloon.
 5. The medical device of claim3, wherein the distal adhesive junction of the first balloon defines alength and the distal adhesive junction of the second balloon defines alength, the length of the distal adhesive junction of the first balloonbeing greater than the length defined by the distal adhesive junction ofthe second balloon.
 6. The medical device of claim 2, wherein the firstballoon is symmetrically positioned within the second balloon, with theproximal adhesive junction of the first balloon being between the firstballoon and the elongate body, the proximal adhesive junction of thefirst balloon and the adhesive junction of the second balloon bothextending within the chamber of the first balloon.
 7. The medical deviceof claim 5, wherein the first balloon is symmetrically positioned withinthe second balloon, the proximal adhesive junction of the first balloonbeing between the first balloon and the elongate body and extendingwithin the chamber of the first balloon, and the proximal adhesivejunction of the second balloon being between the second balloon and theelongate body and extending proximally along the elongate body externalto the chamber of the first balloon.
 8. The medical device of claim 2,wherein the distal adhesive junction and the proximal adhesive junctionof the first balloon extending within the chamber of the first ballooneach define a length of approximately 10% to 30% of a total inflatedballoon length.
 9. The medical device of claim 1, wherein the secondballoon defines a distal face when inflated, the shaft being coterminouswith the distal face.
 10. A medical device for thermally affectingtissue comprising: an elongate body defining a proximal portion, adistal portion, and a lumen therebetween; a shaft slidably disposedwithin the catheter body lumen, the shaft defining a proximal portionand a distal portion; a first balloon disposed within a second balloon,each balloon defining a chamber and having a proximal neck coupled tothe distal portion of catheter body to form a proximal seal, and eachballoon having a distal neck coupled to the distal portion of the shaft,the distal neck of the second balloon forming a distal seal that issubstantially coterminous with the distal portion of the shaft; a fluidinjection conduit disposed within the chamber of the first balloon; thefirst balloon being symmetrically positioned within the second balloon,with the proximal seal of the first balloon comprising an adhesivejunction between the first balloon and the distal portion of thecatheter body and extending within the chamber of the first balloon, andthe proximal seal of the second balloon comprising an adhesive junctionbetween the second balloon and the distal portion of the catheter bodyat a distance proximal to the proximal seal of the first balloon, theproximal seal of the second balloon extending externally to the chamberof the first balloon; the distal seal of the first balloon comprising anadhesive junction between the first balloon and the distal portion ofthe shaft, the first balloon having an outer surface and an innersurface, the distal seal of the first balloon extending within thechamber of the first balloon between the outer surface of the firstballoon and the shaft; the second balloon defining a distal face wheninflated, the shaft being coterminous with the distal face; and theproximal seal and the distal seal of the first balloon each defining alength of approximately 10% to 30% of the inflated balloon length.